The present invention relates to an automatic packing and sealing machine.
A conventional automatic packing and sealing machine mainly includes a plastic film-feeding system, a packing system, a sealing system and a conveying system. The plastic film-feeding system includes a first roller shaft and a second roller shaft which are disposed between two lateral walls. A supporting shaft is passed through each of the roller shafts and two bearings are fitted on two ends of the supporting shaft, permitting each of the roller shafts to freely rotate thereabout. Two adjusting sleeve members are symmetrically freely slidably fitted on the second roller shaft. On an edge of each of the adjusting sleeve members is formed thread holes, whereby screws are screwed into the thread holes to secure the adjusting sleeve member on the second roller shaft. One end of a tension-adjusting shaft penetrates the lateral wall and is formed with a thread section which is cut with a fissure. A coil spring having a central abutting plate is fitted with the thread section with the central abutting plate inserted in the fissure. An outer surface of the coil spring contacts with an inner surface of a cover member. The cover member has a central through hole and a peripheral portion formed with multiple U-shaped recesses, whereby several nuts are screwed on the tension-adjusting shaft to associate the cover member witch a flange plate of the lateral wall. A fixing means is disposed above the flange plate and is composed of a C-shaped seat member, a spring and a fixing rod. The spring is disposed between an upper side of the C-shaped seat and an annular projection of the fixing rod, whereby the spring is able to force the fixing rod into the U-shaped recess of the cover member. A stretching lever is disposed between the lateral walls and has a thread end portion secured on the lateral wall by nuts and a ball end portion.
The packing system includes two slide rails which are disposed on a support body. Multiple linear bearings are fixed on a frame body of a front conveying belt corresponding to the slide rails. A thread sleeve is fixed on a rear portion of the frame body and one end of a thread rod is screwed in the thread rod. The other end of the thread rod is connected with a wheel, whereby when rotating the wheel, the whole conveying belt structure can be moved back and forth. A lower triangular turning guiding board is disposed on a transverse seat located on the frame body. An upper triangular turning guiding board is disposed on an upper transverse rod. A substantially U-shaped stretching lever is disposed on one side of the upper turning guiding board. A blowing tube is diagonally fixed on the frame body under the front conveying belt assembly. The blowing tube is formed with multiple blowing holes, whereby an operater is able to blow diagonally inwardly through the blowing holes in the direction parallel to a diagonal side of the lower triangular turning guiding board.
The sealing system and conveying system include an upper and a lower substantially U-shaped swinging arms which are disposed on two sides of the rear end of the support body. The upper and lower swinging arms are pivotally connected with each other. Two pairs of opposite sensing switch seats are disposed at a front end and on two sides of the upper swinging arm. Sensing switches are respectively disposed on the sensing switch seats. The transverse and longitudinal sealing blades are fixed under the upper swinging arm by screws. On two sides of each of the sealing blades are disposed activating plates which are connected by a substantially U-shaped connecting seat. A pair of opposite sensing plates are fixed above the left and right connecting seats. The left and right connecting seats are formed with through holes through which a guiding rod of the upper swinging arm is passed. A spring is fitted on the guiding rod and two nuts are secured at an upper end of the guiding rod so as to buffer vertical reciprocating movement of the activating plates, whereby during the sealing process, the blowing tube disposed under the front conveying belt assembly is used to blow air into the plastic film to expand the plastic film on the upper turning guiding board and permit the article to be packed on the front conveying belt assembly closer to the transverse sealing blade for saving material and making the package more compacted, and whereby during the conveying process, if the article does not completely pass through the transverse sealing blade or is too close to the longitudinal sealing blade or an unnecessary article or the operator incautiously extends his hand into a position under the sealing blade, when the upper swinging arm is moved downward, before the sealing blades touch the article, the activating plates beside the blades will previously touch the article and be moved upward, so that the sensing plates connected with the connecting seats of the activating plates will ascend along therewith and get close to the sensing switches, making the same sense and emit a signal so as to emergently stop the sealing system for ensuring the safety of the operator, reducing loss of the article and protect the packing and sealing apparatus.
Several shortcomings exist in the above arrangements as follows:
1. The position of the front conveyor set must be frequently adjusted to suit various articles. The adjustment is accomplished by means of a rotary wheel and a cooperative thread rod which rotarily drives the rotary wheel. Such operation is quite laborious and time-costing. PA1 2. The sealing blade is composed of a longitudinal sealing blade member and a transverse sealing blade member connected therewith. A connection portion between the two blade members is sharp and tends to thrust through the plastic film during the sealing operation. This will lead to undesired quality of packing of the article. PA1 3. An electric eye is used to sense the article so as to control the sealing blade of the rear conveyor set to seal the plastic film. However, the electric eye is sensitive only to opaque article while failing to effectively sense a transparent article. Therefore, the sealing blade often fails to seal the plastic film. PA1 4. When packing a relatively high article, the upper triangular board of the front conveyor set can be lifted up by means of the adjusting seat, whereby the plastic film can be properly stretched open and the article conveyed by the front conveying belt can easily pass therethrough. However, the sealing blade of the rear conveyor set is pivotally connected on a blade seat which is fixed on the main body of the machine, so, that when packing the relatively high article, the same is liable to touch the sealing blade. This will disable the sealing blade from performing the sealing operation. PA1 5. When packing a relatively high article, the upper and lower plastic films passing through the upper and lower triangular boards will be spaced by an increased distance. Accordingly, when the sealing blade thermally seals the upper and lower plastic films, the angle contained thereby is increased and the plastic films tend to slightly contract toward the article. This will lead to crimps of the plastic films after sealed. Moreover, the inward contracting plastic films will result in that the clamping chain cannot clamp the plastic films.